1. Field of the invention
The present invention relates to a printed circuit, and more particularly to twisted connecting conductor lines between parts in a printed circuit.
2. Description of the prior art
When a signal is transmitted to a subsequent stage from a high-frequency signal source such as a highspeed CPU, undesired electrostatic or magnetic induction on printed conductor lines in a printed circuit will increase with the increase of the length of such printed conductor lines, and such elongated printed conductor lines are liable to pick up noise signals from the exterior or radiate noise signals to the exterior. In the case where two parts which are to be connected cannot be put close to each other, a coaxial cable or an insulated conductor may be preferably used in place of printed conductor lines.
However, such an exterior cable or conductor is large, compared with printed conductor lines, and therefore, the use of such an exterior cable or conductor will prevent reduction of printed circuit size. Also, disadvantageously, the number of the parts to make up a printed circuit increases, and extra-complicated connecting work is required.
A conventional printed circuit has a conductive grounding layer attached to the surface of its dielectric circuit board opposite to the surface bearing a printed circuit pattern. A conventional multi-layer printed circuit has conductive grounding layers each sandwiched between upper and lower circuit pattern laminations, thereby providing a shielding effect. This sort of shielding structure is, in fact, impractical because a substantial transmission loss will be caused by an increased stray capacity appearing between the grounding conductive layer and the signal path pattern. When a circuit pattern is partly curved in an attempt to permit the signal path to extend around a selected circuit part on the printed circuit, the inductance of the curved path will increase, deteriorating the high-frequency transmission characteristics accordingly.